Source: the liner notes of the 2003 Columbia/Legacy CD release (507880 2).
Delaney Bramlett: ".....Duane Allman is on guitar with me, Kenny Gradney on
bass, and Sam Clayton on congas."

Because of contractual problems Duane is very low in
the mix on 'A Good Thing (I'm On Fire)'.
This album was originally released on 8-track tape as 'Country Life' (Atco
M-8383, 1972).
Atco sold Delaney &
Bonnie's contract and the master tapes to CBS, who released it as
'D & B Together' on the Columbia label with the tracks in
another sequence and 'Try A Little Harder' replaced by 'I Know How It Feels To
Be Lonely'.
'A Good Thing (I'm On Fire)' was re-mixed and the guitar solo at the end of the
song was edited out.

Listen to the
8-track version of 'I'm On Fire' here:

According to Stuart Winkles' article 'Duane Allman: Skydog's Sessions '68-'71'
(published in 'Goldmine', April 11, 1986, Vol. 12 No. 8, Issue 149) Duane also
plays on tracks 3, 4, 6, 8 & 10.
But according to the liner notes of the 2003 Columbia/Legacy CD release (507880 2)
the guitar players on "Comin' Home" are Delaney Bramlett, Eric Clapton and Dave
Mason and on "Groupie (Superstar)" Eric Clapton is featured on guitar.
And the liner notes of the 1990 CD 'The Best Of Delaney & Bonnie' (Rhino
8122-70777-2) mention that the slide guitar on "Comin' Home" and "Groupie
(Superstar)" is played by Dave Mason.
In the liner notes of the 1988 box set 'Eric Clapton: Crossroads' (Polydor
835-261-2) Duane isn't mentioned either on "Comin' Home".

Update April 15, 2014:We have information from Atlantic Records that
shows that "Only You Know And I Know", "Comin' Home" and "Groupie (Superstar)"
were recorded with Eric Clapton. The master numbers for these tracks were
assigned on November 10, 1969.

Update November 13, 2017:Bonnie Bramlett told Scott Cantor that it is not Duane Allman, but Eric
Clapton who played on "Groupie (Superstar)".

45 rpm single releases:Comin' Home / Groupie (Superstar) (Atlantic (UK) 584308, November 1969; Atco SD-45-6725,
January 1970) (Duane
Allman does not play on these tracks)

God Knows I Love You / Only You Know And I Know (Atco
SD-45-6838, 1971)
(Duane Allman does not play on these tracks)